1. Field of the Invention
The present invention relates to an optical transmission device and an optical transmission method that have a function to control an output of an optical signal and transmit an optical signal via an optical transmission line having an optical fiber connected by an optical connector.
2. Description of the Related Art
Conventionally, in an optical transmission system using an optical transmission technique, a technique for controlling an output of an optical signal has been proposed (for example, see Japanese Unexamined Patent Application Publication No. 2006-287649).
In the known technique, when reflected light on an optical connector end face is detected, it is determined that an optical fiber is disconnected from the optical connector, and the output of the optical signal is reduced to a safe level.
However, in the above-described known technique, in some cases, it is difficult to perform the control operation of the optical transmission system.
In the above-described known technique, the optical output is controlled based on a detection of reflected light from the optical connector end face. However, in the optical transmission system, in addition to the optical connector disconnection, reflected light due to stimulated Brillouin scattering (SBS) may be generated. In such a case, in the known technique, the detection of the reflected light due to SBS is erroneously determined as the optical connector disconnection. Then, the output of the optical signal is reduced to a safe level, and as a result, SBS is not generated.
In the optical transmission system, if the generation of SBS and the optical output level reduction operation are repeatedly operated in such a way, an optical amplifier for amplifying the inputted optical signal intermittently oscillates. As a result, in some cases, the overall control of the optical transmission system is difficult.
The present invention addresses the above-described problem in the known technique. An aspect of the invention is to provide an optical transmission device and an optical transmission method capable of identifying whether reflected light detected in a system is caused by an optical connector disconnection or SBS, and implementing a control operation of the system based on the identification result.